An Australian nurse who helped set up a field hospital in a Syrian house has described how medics treated "horrific and brutal" injuries while fighting raged nearby.

Brian Moller is an anaesthetic nurse who has been working with Médecins Sans Frontières for the past nine years.

Last month he helped set up and manage a surgical hospital in a rebel-held town in northern Syria.

For security reasons he will not say exactly where the field hospital, a former two-storey family home, is located.

He says the majority of the wounded people brought for treatment are adult males, and some of them have been targeted by regime jets and helicopter gunships during the battle for Aleppo.

He describes the injuries treated at the "basic but very effective" hospital as "in a word, horrific and brutal" and says they are caused by a mix of "large ordnance and small arms fire ... gunshot wounds, a lot of blast wounds".

"We have the resuscitation room with three tables, a small emergency room. Capacity was 12 beds but we had the capability to receive 30 patients at a time.

"We're there under the auspices of the National Syrian Council and the Free Syrian Army. We are fairly close to the action and the front lines are very, very fluid. Clashes and confrontations occur in different areas.

"But we've fairly centrally located in the north so we're able to take patients from many, many different areas all over Syria.

"I was there for the month of July and seeing, hearing and feeling shelling was an almost daily occurrence."

Heavy workload

He says the casualties are a mix of rebel fighters and civilians.

"Most of the victims that we get through the gate are male and most of them adult," he said.

"Women and children we know are victims and we have treated them at the hospital in the past.

"We did hear first-hand reports with some of our patients coming from Aleppo reporting the use of helicopters and jetfighters ... [but] in areas where we were working, we didn't note any of that."

Mr Moller says the network of makeshift Syrian field hospitals is struggling to cope with the stream of casualties coming out of battle zones like Aleppo, where regime forces and rebels are locked in battle.

"This is a country that's reasonably new to conflict on this scale and of this intensity," he said.

"The doctors and medical staff and nursing staff do have good knowledge, but there's a lack of expertise in applying it in this situation.

"And of course this is compounded by human resource problems with huge shifts of populations within the country and by poor resourcing and poor supply.

"It's very, very frustrating. And realistically what we're doing is only a drop in the ocean."

Mr Moller has just finished his assignment at the hospital and was speaking to AM from Paris.